Why do some shooting stars flash or explode?
Bigger space rocks can break apart in the air. Each time they break, they suddenly get brighter, making a flash or flare.
Most shooting stars are smooth streaks of light. But sometimes a bright one suddenly flashes, flares or seems to explode. Here is why.
Bigger space rocks are not perfectly solid. Many have cracks inside, from being knocked about by collisions in space. As they plunge deeper into Earth's air, the air pushes harder and harder against their front. Eventually, the push becomes too much, and the rock breaks apart.
When it breaks, there are suddenly lots of smaller pieces, with lots of new surfaces facing the hot, rushing air. More surface means more material heating up and glowing at once, so the fireball suddenly gets much brighter. This is the flash or flare you see. Sometimes it happens several times as pieces keep breaking.
Very bright exploding fireballs are called bolides. Some are so bright they light up the ground like daylight for a moment. If the explosion is big enough, people on the ground might hear a boom a minute or two later, because sound travels much more slowly than light.
When a space rock breaks apart, its pieces sometimes survive and fall to the ground as meteorites, spread out over a long area called a strewn field.